The present invention relates to a vehicle seat, and more particularly, relates to the frame structure of a seat bottom of a vehicle seat.
As a prior art, Japanese Utility Model Application Laid-Open No. 5-35458 discloses a seat bottom of a vehicle seat, which comprises: a framework including a pair of left and right side frame members extending in the back-and-forth direction, a front frame member fixed between front portions of the side frame members, and a rear frame member fixed between rear portions of the side frame members; a plurality of zigzag springs positioned between the front frame member and the rear frame member, and having spring tip ends attached at the middle portion between the front portion and the rear portion of the side frame member; a cushion attached on the framework with the springs; and a height control mechanism moving the framework up and down relative to a vehicle body.
The prior art has such a disadvantage that the thickness in the vertical direction of the seat bottom is thick. It will be described below. As shown in FIGS. 23 and 24, the framework 100 of the prior art has a bracket 102 fixed to a bottom 101 of the framework 100, and the bracket 102 is connected to a slide rail 104 by way of a height control mechanism 103. The height control mechanism 103 has a leg portion 105 fixed to the bracket 102, an arm 107 connected to the tip of the leg portion 105 by a shaft 106, an interlocking shaft 108 to which the base portion of the arm 107 is fixed, an operating dial 109, an output gear 110 arranged to be rotated by the operating dial 109, and a sector gear 111 meshed with the output gear 110 and fixed to the interlocking shaft 108. The dial 109 is supported by a bracket 112 of the slide rail 104.
In the case of the prior art with the above structure, the framework 100 has the integrally fixed bracket 102, and therefore, the vertical height of the framework 100 is shown by H. Therefore, the zigzag spring 113 is positioned at a higher position of the framework 100, and the position of the cushion that is mounted on the spring 113 also inevitably becomes high, so that the thickness in the vertical direction of the seat bottom is increased.
Furthermore, in the case of the prior art, the fact that almost all members of the height control mechanism 103 are provided at positions lower than the upper end of the bracket 112 of the slide rail 104 is also the reason why the vertical thickness of the seat bottom is increased.
It is an object of the present invention to provide an improved vehicle seat that overcomes the disadvantage of the prior art.
In order to achieve this object, a vehicle seat is provided, which comprises: a framework composed of a pair of left and right side frame members that extend in the back-and-forth direction, a front frame member that has left and right side plates fixed to the front portions of the side frame members, and a rear frame member that has left and right side plates fixed to the rear portions of the side frame members; a plurality of zigzag springs that are positioned between the front frame member and the rear frame member, and have spring tip ends attached at the middle portion between the front portion and the rear portion of the side frame member; and a height control mechanism that moves the framework up and down relative to the vehicle body, and which is characterized in that each of the spring tip ends is arranged at a position near the center line vertically dividing the side frame member, and the distance between the spring tip end and the center line is made shorter than the distance between the spring tip end and the upper edge of the side frame member.